Reading a tract modifies your alignment, pieties, and corruption state.
Tracts have finite uses, measured in turns of reading. This is initially set to 1d1000 for a brand new tract. Each time you attempt to read a tract, you will spend 20d10 turns reading it, or the remaining time, whichever is smaller.
While you are reading a tract, your body armor cannot be damaged, and teleportitis is disabled, in addition to the normal effects of a long action.
If you are interrupted, no further effect will occur. There is code which appears to give a reduced effect if spent less turns, but it has no effect because you don't get any further than here if interrupted.
In the formulae below, T is the number of turns spent on this reading.
Piety effects from reading tracts are "raw" piety changes; they do not result in the typical -1/30 other god effect. If your piety with some god is reduced to or below -500 by a tract, you will suffer negative piety effects (inventory cursing, etc), unless your god deflects them. Your god will never deflect his own penalties, and will deflect the penalties of other gods if and only if your piety with your current god is greater than one-eighth of the absolute value of the punishing god. Deflection does not cost piety.
Angering the neutral god with a tract is incorrectly reported as "the anger of Order".
|Tract||Corruption||Lawful piety||Neutral piety||Chaotic piety||Alignment|
|order||-T CPs||+T/2||-T/2||-T/2||T/10 stones towards L+|
|balance||No effect||No change||+T||No change||T/10 stones towards N=|
|chaos||+T CPs||-T*2||-T*2||+T*2||T/10 stones towards C-|
There are two very different things you can do with spellbooks, learning and casting. To cast, you must already know the book's spell; bookcasting costs 3000 energy and thrice, twice, or half again more power than normal casting depending on talents. It does not add effectivity or deplete knowledge. The remainder of this section will be dedicated to learning.
Reading a spellbook takes 3 + base cost turns, succeed or fail.
There are 11 possible bonuses to learning a spell. They are added together to gain the percentage chance of success.
First is a term dependant only on your class. Priests and wizards have +30, mincrafters -40, other classes in between.
Next is a term proportional to your Learning. The constant of proportionality is 1/8 for Barbarians, 3 for Wizards, and in between for others.
Next is a term dependant only on the spell. Farsight has +6, Wish has -100, other spells in between.
Next is a spell type term. Pure spellcasters (except elementalists) attempting to learn purely arcane spells get -10, other combinations get +10. This is probably a bug; wizards are penalized for arcane spells.
Next, you are penalized -1 per remaining turn of drunkenness.
Next, you are rewarded +20 for a blessed book and penalized -20 for cursed.
Next, you are rewarded for your level. Pure spellcasters gain 2*level with a maximum of 75. All other non-Mindcrafter non-trolls get 1*level. Mindcrafters and trollish non-casters get nothing.
Next, you are rewarded +1 per 5 Concentration.
Next, you are rewarded +1 per 10 Literacy.
Next, Druids and Necromancers receive +40 for their specific starting book.
Next, characters born under Book receive +20.
Now, there is a straight Literacy check - no effect good or bad will occur unless you make a Literacy in 100 check (max 99%).
Next, a 1d100 is compared to your total success. If it's less or equal, you succeeded; the amount of knowledge you gain depends on the margin of success (total bonuses - die roll). If it comes up higher, you fail. There is a margin of safety depending on your class. Wizards and Elementalists need to flub the success roll by a margin of 50 or more to see a bad effect; if their basic success chance is at least 50, they will obviously never see any bad effect. Barbarians and Mindcrafters have no margin; every failure is bad. If the die langed in the margin zone, no good or bad effect occurs.
On bad failure:
There are 11 equally probable failure modes. 1. Spellbook bursts into flames and is destroyed. Lose spellbook, no further effect. 2. Your magical energy drains away. Deduct twice the spell's base cost. No effect if PP already 0. 3. You are confused for 5dCOST turns. 4. You are stunned for 4d(COST/2) turns. 5. You take 1dCOST damage. (Spellbooks of wish are dangerous things...) 6. Spellbook "explodes" in a ball of fire. Take 4d(COST/4) FIRE damage and inventory damaged as for fire, but no actual explosion occurs. Spellbook destroyed. 7. You are blinded for 2dCOST turns. 8. You are teleported. On a non-teleport level, confuse 5d5 turns instead. 9. -1 Toughness, permanently. 10. The spellbook suddenly is gone! 11. A pit opens up beneath you! Yes, counts as gravedigging.
You gain castings and train Learning. Learning training is 2*base cost, or base cost / 2 if you had castings already.
Castings gained are initially min(200 + Le*4, max(20, max(5, success margin - existing castings) * max(1, Le / 4))). If you have 30 or more castings, the formula used is instead max(5, max(1, Le/8) * success margin).
Casting gain is reduced by existing castings and level - it is multiplied by 100 - 3 * (castings / 50 + level / 3) and divided by 100. Reduction is never worse than a 25% multiplier and never reduces below 1.
Cup is +20%, Good and Great Book Learner are each +10%.
Successfully reading a book deducts one charge. Books start with 2d3 charges and disappear when it reaches 0.
Black Tome of Alsophocus
Corrupts while merely carried. When you finish reading it, you are additionally corrupted by 20 points per turn spent, minimum 200, maximum 6666. Therefore, you should always read the black tome in half reading time rooms. Additionally, you should have a wimpy monster near you; if the reading goes on for too many turns, allow yourself to be interrupted to avoid massive corruption.
The black tome counts as a book of a uniform random spell; Wish and Darkness are equally likely.
The black tome cannot be destroyed. If a failure would destroy it, the next entry in the list is used instead.
Pay attention to the weights of books. The Black Tome of Alsophocus is (400s). A black tome (100s) is an ordinary spellbook.